import java.util.Stack;

public class Test3 {
    public static void main(String[] args) {
        Stack<Integer> stack = new Stack<>();
        boolean b1 = stack.empty();
        boolean b2 = stack.isEmpty();
        System.out.println(b1);
        System.out.println(b2);

        stack.push(12);
        stack.push(23);
        stack.push(34);
        stack.push(45);

        int ret = stack.pop();
        System.out.println(ret);

        int ret2 = stack.peek();
        System.out.println(ret2);
        int ret3 = stack.peek();
        System.out.println(ret3);

        boolean b3 = stack.empty();
        boolean b4 = stack.isEmpty();
        System.out.println(b3);
        System.out.println(b4);
    }
}
